Oil recovery process

ABSTRACT

An oil recovery process which employs, as an additive to the aqueous material used for waterflooding, at least one of the reaction product of sulfamic acid and a polyethoxy alcohol or, the ammonium sulfate slat of a polyethoxylated alkylphenol is disclosed.

0 United States Patent 1151 3,659,650 Stratton May 2, 1972 s41 OILRECOVERY PROCESS 2,454,544 11/1948 Bock et al ..252/342 x 2,454,54511/1948 Bock et a1. ..252/342 UX [72] Inventor: Charles A. Stratton,Bartlesvllle, Okla. 3,308,883 3/1967 Foster "166/275 [73] Assignee:Phillips Petroleum Company 3,508,612 4/1970 Reisberg et a1. 166/274 [22]Filed: June 1970 Primary Examiner-Stephen .i. Novosad [21] App]. No.:46,552 Attorney-Young and Quigg 52 us. c1. ..166/275, 252/8.S5 D [57]ABSTRACT [51] Int. Cl. ..E21b 43/22 An oil recovery process whichemploys, as an additive to the [5s 1 Field 61 Search ..166/273-275;aqueous materia! used for walerflooding. at l t one of the 252/35 5 1342 reaction product of suifamic acid and a poiyethoxy alcohol or, theammonium sulfate slat of a poiyethoxylated alkylphenoi is [56]References Cited dlscbsed' UNITED STATES PATENTS 8 Claims, No Drawings3,500,923 3/1970 Reisberg 166/274 OIL RECOVERY PROCESS This inventionrelates to a process for secondary recovery of crude oil bywaterflooding.

ln an application Ser. No. 858,855 filed by me on Sept. 17, 1969, nowU.S. Pat. No. 3,583,486 and incorporated herein by reference, there wasdisclosed and claimed a method for producing oil from an oil-bearingstratum. That method employed a polyethoxy alcohol having eight to 12ethoxy units as an additive to, or a component of, an aqueous fluiddrive.

it has now been determined that compounds which are the reactionproducts of sulfamic acid and such polyethoxy alcohols are usefulwaterflood additives. Relatedly, it has been determined that theammonium sulfate salts of polyethoxylated alkylphenols are similarlyuseful waterflood additives, either as such, or when polymerized to formthe ammonium sulfate salt of the ethoxylated poly-molecule. Thisinvention provides a process for the use of such waterflooding agents.

According to this invention there is provided a process for producingoil from an oil-bearing stratum which comprises injecting into thestratum an aqueous slug containing an effective amount of a surfaceactive-viscosifier additive agent selected from the group of compoundshaving the formulas:

in which R is a halogen, alkyl, cycloalkyl, or an oxyalkyl group havingeight to 12 carbon atoms and n has an average value of from 3 to 8, and

. in which R is defined above, m has a value from 1 to 5, and n has anaverage value of from about 8 to about 1 1.25, driving the injected slugthrough the stratum so as to displace the oil from the stratum, andrecovering the displaced oil.

The compounds of the invention and complying with the above formulaswill be referred to hereinafter as compound (a) and compound (b).

Accordingly, it is an object of this invention to provide a moreefficient method of oil recovery.

Either of these compounds can be prepared in a number of ways. Theprecursor of compound (a) is a polyethoxylated phenol. This material isconverted to its ammonium sulfate salt by reaction with sulfamic acid.Some of its preferred embodiments are derived in this manner fromethoxylated phenols, the ethoxylated phenols being availablecommercially as lgepal CO 210, lgepal CO 430, lgepal CO 520 and lgepal530 from Antara Chemical Corp., New York, N.Y. Preferably, theconversion is conducted at temperatures of between about 110 and about150 in the presence of urea or an amide, such as acetamide as thecatalyst, the catalyst being present in an amount of 3-10 g/ 100 gethoxylated alkylphenol. Generally, the reaction temperature will beabout 135 C. at a reaction time of about 4 hours. The sulfamic acid isemployed in stoichiometric amounts or in a slight excess of about 10percent. The lgepal is selected in accordance to the number of ethoxygroups, that is, n, desired in the product.

The precursor of compound (b) is the ethoxylated polymolecule whosepreparation is described in the aforementioned application. Thisethoxylated poly-molecule is then reacted with sulfamic acid to convertits chain terminal OH group to O-SO Nl-L, the ammonium sulfate saltform, in a manner similar to the preparation of compound (a).

Various forms of compounds (a) were prepared by the method described inthe following examples.

In a stirred flask, g of polyethoxylated nonylphenol (lgepal CO 210, n3) and 4 g of acetamide were heated to C. Twenty-seven grams of sulfamicacid were gradually added, the temperature being maintained betweenl35-l40 C. for about 2 hours. The product was recovered as a stickysolid.

This preparation procedure was repeated employing like quantities ofeach of the following lgepal compounds to produce ammonium sulfate saltsof the polyethoxylated alkylphenols in which n has the value shown:

lgepal C0 430 4 n 1 lgepal CO 520 n 4 lgepal CO 530 n 5 Variouscompounds (b) were prepared by the method described in the followingexample, the preparation being i1- lustrated employing an alkylphenol,as the starting compound.

Two hundred and three-tenths grams or 1 mole of nonylphenol and 1.23 gof sodium were allowed to react in a stirred reactor at 125 C.incrementally, 22.54 g fonnaldehyde in the form of paraformaldehyde wereadded during which addition the temperature was increased to C. After 45minutes, the temperature was increased to 205 C. and water vapor wasvented from the reactor. Gaseous ethylene oxide was introduced into thereactor at a rate of about 1 g per minute until 375 g (8.5 moles/mole ofnonylphenol) had been added to the reaction mixture. During thisaddition, the temperature was permitted to increase from about 60 C. toabout 205 C.

One hundred grams of the above product were sulfated employing thosequantities of reactants and that procedure employed in the preparationof compound (a).

Preparations were made with a compound having four methylene linkedmolecules, i.e., m is 4, in which the number of ethoxy groups, i.e., n,on each of the methylene linked molecules had average values of 8, 8.5,9, 9.5, 10 and 11. Mixtures of these compounds were then prepared inwhich m was equal to 4 and n'had values of 9.62, 9.75, 10.5 and 10.75.

In the practice of this invention, the necessary quantity of the surfaceactive-viscosifier additive agent, such as compounds (a) and (b), isdispersed in an aqueous medium, such as water and brine. The amount ofthe agent employed will be in the range of from about 0.01 to about 5weight percent of the aqueous medium. Quantities of the aqueous mediumemployed are those conventional within the art as are the methods ofemployment of the aqueous medium, and amount to from about 0.01 to about2 pore volumes. The usual extraneous materials can be included in theaqueous solution, these including CaCl MgCh, etc.

Use of the compounds of the formula (a) of this invention were evaluatedby the microslide technique described in U.S. Pat. No. 3,362,474, issuedJan. 9, 1968 to Heino Purre using Nacatoch sand. By this technique, theabove-prepared compound (a) produced the following results whenemploying aqueous solution containing 1.0 weight percent of thecompound, in relation to the value of n in their formula:

n Value Effectiveness 1 None 3 Very 4 Very 5 Slight 5 tion of 600 ml ofthe solution, that is an amount of 2.5 pore volumes, results were asshown below. For comparative purposes, data relative to a nonsulfatedpolyethoxylated nonylphenol having an average value of 9.5 is included.

The above data indicate the effectiveness of the compounds (a) of thisinvention particularly in those embodiments in which n has a value of 3through 5.

Use of the compounds of the formula (b) of this invention was evaluatedby the two aforementioned techniques under substantially identicalconditions.

Results employing the microslide technique, as related to the n valuesof the compounds were as follows:

n Value Effectiveness 8 None 9 Good 9.75 Good 10 Good 10.5 Very good10.75 Excellent 1 1.0 Poor The results of the 6 foot sand tube testswere as follows:

n Value oil Production, ml.

The above data indicate that compounds of formula (b) in which n has avalue between about 8.5 and 10.9, and preferably between about 9.0 and10.75, provide excellent results when used as waterflood additives.

In respect to some seeming discrepancy between the results of the abovetests, it is recognized that such discrepancies are common. However,considering the nature of the tests in comparison to actual conditionsunder which such compounds are employed, both tests permit considerablepredictability of results in actual usage, the 6 foot tube test being,usually, the more predictive.

It will be evident from the foregoing that various modifications can bemade to the method of this invention. Such, however, are considered asbeing within the skill of the art.

I claim:

11. A process for producing oil from an oil-bearing stratum whichcomprises injecting into the stratum an aqueous slug containing aneffective amount of a surface active-viscosifier additive agent havingthe formula:

in which R is a halogen, alkyl, cycloalkyl, or an oxyalkyl group havingeight to 12 carbon atoms and in which n has an average value of from 3to 8, driving said slug through said stratum to displace the oil fromsaid stratum, and recovering the displaced oil.

2. The process as defined in claim 1 in which said agent is employed inan amount from about 0.01 to about 5 weight percent of said aqueousslug.

3. The process as defined in claim 1 in which aqueous slug is employedin an amount from about 0.01 to about 2 pore volumes.

4. The process as defined in claim 1 in which said aqueous slugcomprises brine.

5. A process for producing oil from an oil-bearing stratum whichcomprises injecting into the stratum an aqueous slug containing aneffective amount of a surface active-viscosifier additive agent havingthe formula:

in which R is a halogen, alkyl, cycloalkyl or oxyalkyl group havingeight to 12 carbon atoms, m has a value from 1 to 5, and n has anaverage value of from about 8 to about 11.25, driving said slug throughsaid stratum to displace the oil from said stratum, and recovering thedisplaced oil.

6. The process as defined in claim 5 in which said agent is employed inan amount from about 0.01 to about 5 weight percent of said aqueousslug.

7. The process as defined in claim 5 in which aqueous slug is employedin an amount from about 0.01 to about 2 pore volumes.

8. The process as defined in claim 5 in which said aqueous slugcomprises brine.

2. The process as defined in claim 1 in which said agent is employed inan amount from about 0.01 to about 5 weight percent of said aqueousslug.
 3. The process as defined in claim 1 in which aqueous slug isemployed in an amount from about 0.01 to about 2 pore volumes.
 4. Theprocess as defined in claim 1 in which said aqueous slug comprisesbrine.
 5. A process for producing oil from an oil-bearing stratum whichcomprises injecting into the stratum an aqueous slug containing aneffective amount of a surface active-viscosifier additive agent havingthe formula:
 6. The process as defined in claim 5 in which said agent isemployed in an amount from about 0.01 to about 5 weight percent of saidaqueous slug.
 7. The process as defined in claim 5 in which aqueous slugis employed in an amount from about 0.01 to about 2 pore volumes.
 8. Theprocess as defined in claim 5 in which said aqueous slug comprisesbrine.